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Most people equate the hormone cortisol with the experience of stress. Cortisol is released in response to stress, but what if I told you that it helps you feel better after stress? Taking a dose of cortisol can actually reduce the negative effects of stress. These findings counter our expectations but provide important information about how stress and cortisol interact.

Let me back up a minute and explain the time course of the two stress-response systems. During stress, the first system to respond is the sympathetic nervous system. This leads to the classic "fight-or-flight" response. Adrenaline is released from your adrenal glands. Your heart starts pounding, and your breathing gets quicker, all to get you the energy you need to respond quickly to stress.

The next system to respond is the hypothalamic pituitary adrenal axis (mercifully abbreviated "HPA axis"). This is the system that ultimately leads to the release of cortisol. Importantly, this system is considerably slower than the sympathetic nervous system. While the sympathetic nervous system responds within milliseconds, the HPA axis takes a few minutes to respond. From the beginning of stress to the peak cortisol response can take around 10 minutes. In a quick stressful situation, cortisol may not even be released until the situation is over.

What’s cortisol doing if it does not even reach its peak until the stress is over? One of its primary actions is to help in recovery from stress. In our evolutionary history, stress would likely involve injury. Elevated cortisol can help in recovery from these injuries. Stress in modern times is more likely to involve a bruised ego rather than actual bruises. An intriguing line of research shows that cortisol can help with bruised egos.

In a study examining stress responses in a laboratory, people who showed a greater cortisol response to stress showed less negative mood than those who showed a lesser cortisol response. In another study, people who received a dose of cortisol before experiencing stress also showed less negative mood than those who received a placebo. These results suggest that cortisol has a mood-buffering effect. It helps keep our negative mood in check in response to stress.

Why would this be the case? In addition to preparing us to respond to stressful situations, our stress physiology (especially cortisol) helps us recover from the effects of stress. This is true in the body, where cortisol helps to reduce inflammation. It is also true in the brain, where cortisol attaches to specific receptors involved in mood, which help us return to our pre-stress emotional states.

Clinical work has capitalized on these findings to examine the impact of cortisol on symptoms of disorders such as phobias and PTSD. One remarkable study in people with social phobia examined the impact of a single dose of cortisone (a synthetic version of cortisol) on fear responses to a social stressor. Results showed that cortisone reduced reports of fear and reduced heart rate responses during social stress compared to a placebo.

These surprising effects of cortisol on mood provide a nice example of the "wisdom of the body." The hormone released in response to stress ultimately works to repair the damage done by stress, both in the mind and the body. This balancing act that our stress system manages is precarious, though. Chronic stress can overwhelm the system leading to poor mental and physical health. As always, the key is to maintain balance.